So in normal GearVr-Apps, which you can download from the marketplace, you can activate the GearVr Menu to control brightness etc. with a long click on the back button. But this does not work for all of my apps which I made with Unity for the GearVr, is there something special I have to import into my project?
Have you installed the utilities for Unity? According to the docs, the long click on the back button should always show the GearVr Menu. But, if it is not working, there is also a script (OVRPlatformMenu.cs) in the utilities that does that. You can find more info about the script here.